his relationship with broadwell came to light during an fbi investigation that began last summer. today, attorney general eric holder defended the bureau's decision not to alert president obama and congressional leaders. >> we made the determination as we were going through the matter that there was not a threat to national security. had we made the determination that a threat to national security existed, we would of course have made that known to the president and also to the appropriate members on the hill. >> holman: that investigation also has led to a pentagon probe of the top u.s. commander in afghanistan-- marine general john allen. he's under scrutiny for extensive communications with a tampa, florida woman. allen has denied wrongdoing. defense secretary leon panetta said today no other senior military officials appear to be involved. he spoke during a trip to thailand. >> i'm not aware of any others that could be involved in this issue at the present time. obviously as this matter continues to be investigated both on capitol hill and by the inspector general, i'm sure we